Changes in extracellular matrix components of bladder detrusor in relationto bladder hypertrophy and compliance in patients with benign prostatic hyperplasia

The bladder hypertrophy caused by infravesical obstruction due to benign pr ostatic hyperplasia (BPH) often results in bladder dysfunction. Here we att empted to study morphometrically the histological changes in bladder detrus or with reference to extracellular matrix and to find the correlation of th ose changes with bladder hypertrophy. Ultrasound estimated bladder weight ( UEBW) and urodynamic parameters were evaluated in 34 BPH patients (71.4+/-7 .9 years) before surgery. Bladder wall samples were obtained at surgery and stained using Masson trichrome method and immunohistochemistry for collage n types I and III and fibronectin, followed by morphometric color image ana lysis system. UEBW, ratios of connective tissue-to-smooth muscle (c/m), col lagen type Ill-immunoreactive area-to-collagen type I-immunoreactive area ( collagen III/I) and fibronectin-immunoreactive area-to-non-immunoreactive a rea (f/n) ranged from 21.0 to 126.1 g (47.9+/-25.4 g), 12.9 to 53.3% (27.6/-9.2%), 31.9 to 69.7% (46.5+/-8.0%) and 40.2 to 125.9% (59.8+/-15.9%), res pectively. UEBW correlated with c/m (r=0.744, p<0.0001), collagen III/I (r= 0.698, p<0.0001) and f/n (r=0.733, p<0.0001). Among urodynamic parameters, bladder compliance was the only one that correlated with c/m (r=0.673, p<0. 0001), collagen III/I (r=0.475, p<0.05) and f/n (r=0.590, p<0.001). These r esults suggest that an abnormal increase of connective tissue accompanied w ith increased levels of collagen type III and fibronectin could contribute to advanced bladder hypertrophy with a loss of elasticity of the bladder wa ll in patients with infravesical obstruction.